W212 facelift LED headlamp problem

[CiderAndy]

A few days ago I started my car up and was met with a warning saying "Left daytime driving lamp". A visual check showed the DRL was not working. Later that day it worked again but it hasn't worked since. The headlamps are switched to auto and as dusk fell and the headlamps came on another warning came up, this time "Front left parking lamp". A search around the internet showed it's a fairly common fault, although I didn't find a report of both happening at the same time. The headlamp is working fine.

I understand the DRLs are controlled by the front SAM under the bonnet and that once a fault is detected, the SAM cuts off the supply to the DRL thereby making voltage checks on the wiring with a multimeter redundant. My intention is to remove the headlamps and connect right lamp to left wiring and left lamp to right wiring to see if the problem remains on the left side or moves to the right side, thereby eliminating a fault in the supply or a fault in the headlamp unit. But as I'm seeing two faults, on different circuits, I'm already suspecting it's internal to the headlamp rather than on the supply side.

Any thoughts or suggestions?

 

[E280Tim]

A few days ago I started my car up and was met with a warning saying "Left daytime driving lamp". A visual check showed the DRL was not working. Later that day it worked again but it hasn't worked since. The headlamps are switched to auto and as dusk fell and the headlamps came on another warning came up, this time "Front left parking lamp". A search around the internet showed it's a fairly common fault, although I didn't find a report of both happening at the same time. The headlamp is working fine.

I understand the DRLs are controlled by the front SAM under the bonnet and that once a fault is detected, the SAM cuts off the supply to the DRL thereby making voltage checks on the wiring with a multimeter redundant. My intention is to remove the headlamps and connect right lamp to left wiring and left lamp to right wiring to see if the problem remains on the left side or moves to the right side, thereby eliminating a fault in the supply or a fault in the headlamp unit. But as I'm seeing two faults, on different circuits, I'm already suspecting it's internal to the headlamp rather than on the supply side.

Any thoughts or suggestions?

Did you get to the bottom of this issue? My E350 has just thrown up a parking light failure warning.. 2 days after replacing the number plate light